This invention generally relates to a method and apparatus for venting air from a wheel end assembly.
Vehicle wheel end assemblies experience air pressure build-up within the wheel end during vehicle operation, which is undesirable. This air pressure is vented from the wheel end via an outlet. Air pressure build-up can occur within a wheel for various reasons.
For example, air pressure can build up within a wheel end for a vehicle having a central tire inflation system (CTIS). CTIS are typically connected to multiple wheel ends on a vehicle to maintain a desired optimal tire pressure at each wheel end during vehicle operation. The CTIS provides a separate air supply, or utilizes an existing air supply on the vehicle, which is connected to each tire. During vehicle operation, the pressure in each tire is monitored and when the tire pressure falls below a predetermined optimal pressure, the CTIS supplies air to inflate the tire back up to the optimal tire pressure. The CTIS includes multiple seals at each wheel end to provide a sealed system that allows air to be transferred from a stationary source on the vehicle to a rotating wheel component.
Each wheel end includes oil or other similar fluid that lubricates wheel end components to prevent component wear and overheating. A certain level of fluid needs to be maintained in each wheel end to provide sufficient lubrication. During vehicle operation, CTIS seal leaks cause air pressure to build up in the wheel end assembly, which is undesirable.
Air pressure build-up can also occur in wheel end assemblies for vehicles that do not include CTIS. For example, temperature increases within the wheel end assembly, due to vehicle braking operations, can cause air pressure to be built up within the wheel end. Also, the churning of the lubrication fluid within the wheel end assembly from a bearing and/or wheel end gear assembly can cause pressure build-up.
This air pressure is vented from the wheel end assembly via an outlet port. In current wheel end configurations, as the air is vented, some of the wheel end lubricating fluid is also vented out through the same outlet port. This causes lubrication fluid levels within the wheel end to decrease over time, resulting in potential premature component wear.
Thus, it is desirable to have a vehicle wheel end assembly that is capable of venting air pressure from the wheel end while maintaining sufficient levels of lubricating fluid, as well as overcoming the other above mentioned deficiencies with the prior art.
A vehicle wheel end assembly includes a blocking member that reduces the amount of lubricating fluid in a wheel end assembly that is vented from the wheel end during exhaustion of air via a vent path. The blocking member is positioned within the wheel end to limit the amount of lubrication fluid that enters the vent path.
In the preferred embodiment, the wheel end assembly includes a wheel hub and a wheel end gear assembly in driving engagement with the wheel hub. A fluid chamber, formed within the wheel hub, defines a fluid path in communication with the wheel end gear assembly to provide lubricating fluid to the wheel end gear assembly. A vent path extends from the wheel end gear assembly, through the wheel hub to an outlet for venting air from the wheel end. The blocking member is positioned within the wheel hub to at least partially block the fluid path to reduce the amount of lubricating fluid that enters the vent path as air is vented from the vent path via the outlet.
In a disclosed embodiment, the wheel end includes a spindle that is mounted to an axle housing. The spindle has a bore that extends through the center of the spindle. The wheel hub is supported on the spindle via at least one bearing for rotation relative to the spindle. An axle shaft is mounted within the spindle bore for providing driving torque to the wheel hub. The wheel end gear assembly reacts between the wheel hub and the axle shaft to transfer driving torque from the axle shaft to the wheel hub. The vent path is defined within the hub and extends at least from the gear assembly through the bore to the outlet. The blocking member extends outwardly from one end of the spindle to at least partially block the fluid path to reduce the amount of lubricating fluid that enters the vent path as air is vented from the outlet.
Preferably, the blocking member is a cylindrical sleeve that has an outer surface and an inner surface. The outer surface is in engagement with the inner bore of the spindle. The axle shaft extends through the center of the sleeve and is spaced from the inner surface to define a gap that forms a portion of the vent path. The sleeve extends outwardly from one end of the spindle such that the outer surface blocks a portion of the fluid path.
The subject invention allows air to be easily vented from the wheel end while still maintaining sufficient lubrication levels within the wheel end assembly. These and other features of the present invention can be best understood from the following specifications and drawings, the following of which is a brief description.